Gas bag modules have become part of the standard equipment in passenger cars. For this reason, their installation should of course be able to be carried out quickly and at a favourable cost, without any curtailment to safety. Detent connections present themselves for this purpose, in which for example detent hooks connected with the gas bag module engage into a complementary detent element on a vehicle-fixed component, e.g. a spring wire, in order to connect the gas bag module with the vehicle in a secure and load-bearing manner. Such a detent connection can be produced in a very time-saving manner. However, in detent connections of this type, an incorrectly locked state can occur in which the detent elements are in fact already in contact with each other, but the detent hook has not yet engaged behind the spring wire correctly. As the locking mechanism generally can not be seen from the exterior, such incorrect lockings are difficult to detect. Of course, it must be ensured that the detent connection is correctly closed and the gas bag module is securely fixed in the vehicle. Checking takes time and therefore makes the installation more expensive. It is, therefore, an object of the invention to provide an option for quickly and simply detecting such detent connections which are not correctly locked.